The present invention relates to a one-way clutch mounted on a rotatable shaft for use in a packing machine or an office machine such as a copying machine, a facsimile, a printer and a typewriter.
In general, a bearing-type one-way clutch is composed of an outer race, an inner race and sprags interposed therebetween to function to transmit torque to produce the rotation of the outer or inner race in one direction and to allow the inner or outer race to idle in the other direction.
In the prior art technique, a plurality of sprags d serving as torque transmitting members are retained in a retainer c between the outer race a and the inner race b as shown in FIG. 3a. Said sprags are oriented at such an angle that opposite ends d.sub.1 of each sprag maintain sliding contact with the outer race a and the inner race b when inclined clockwise and that the ends come into locking engagement with the outer race a and the inner race b when inclined counter-clockwise. Further, each said sprag d is normally urged toward a position to allow the same to incline counter-clockwise by means of a spring e.
In this structure, each sprag is inclined counter-clockwise against the spring e when the outer race or inner race is rotated in a direction as shown by P or P' (FIG. 3a). In this state, the outer race and inner race have no locking engagement with each other such that an idling position is taken. When the outer or inner race is rotated in a direction as shown by q or q', each sprag d is jammed or gripped between the outer and inner race to establish a locking engagement therewith for the transmission of torque (FIG. 3b).
However, in the above-mentioned structure, the retainer is provided independently of the outer or inner race. Further, the springs as part of torque transmitting means are incorporated into the retainer, making the structure complicated for assembly. Furthermore, the operation varies depending on the state of the spring. In an idling state, the resiliency of the springs is applied to the outer or inner race through the sprags so that the rotation of the outer or inner race becomes dull.
Still further, the prior art one-way clutch has a serious drawback that there is a backlash when the operation is to be shifted from idling to clutching since retainers c are not rigidly provided between the outer race a and the inner race b.